Your Site Slogan

25th July 2017

The venue for Society meetings has changed and the directions to it given on p. 126 of the July 2017 issue are incorrect. Meetings are held at the Hall of St. Botolph’s Church, Bishopsgate, London EC2M 3TL. The Hall is set in a small garden behind the church, less than 2 minutes’ walk from Liverpool St. mainline and underground stations.

Solution: An excellent ambush key 1.Rh1 prepares the pin necessary to make
the threat 2.hxg4 work. The problem has been described as showing tertiary
black correction. Secondary correction occurs where a random move of a
defending piece contains an error which White exploits, while a specific
move contains an element which compensates for that error, but also
contains a second error which allows a new mate. This can be seen in the
play of the g4 knight. A random move defends by vacating g4, but opens the
line e2 - h5, allowing a bishop check at e2 which mates because it is
double check. 1...Se5 also allows the bishop check, but corrects by
preventing the rook check. The new error is interference with the a1
bishop, allowing 2.Sg7. It is claimed that the sequence 1...Bg6 random,
1...Bf5 and 1...Bf7 shows tertiary correction. A random move defends by
leaving a flight square at g6 but allows a bishop check at e8. 1...Bf5 is
another secondary correction, again preventing a double check by closing
the rank, but interfering with the f8 rook and allowing 2.Sf4. 1...Bf7
again interferes with the rook, and corrects against 2.Sf4 by pinning the
knight. The new error is unguard of f5, allowing 2.Qf5. To my way of
thinking this is not a true tertiary correction, because 1...Bf7 does not
commit the random error of allowing the bishop check at e8. There is
by-play 1...Rd4 2.Sg7, 1...Rf4 2.Sxf4, and 1...Qe2, Qxe3, Qb4, Qg1 or Qxh1
2.Qh4.

However the main idea is defined, the problem is certainly a memorable one.

Any comments or questions on this problem should be addressed to
Michael McDowell using the ‘Contact’ item in the menu on the left.